Turn signals for a bicycle

This was a part of an engineering class project at Purdue which I decided to fully develop.

The premise of this project was to introduce a solution that would help reduce the number of mobility-related accidents around campus.

The main device is mounted to the bicycle by a clamp to the seat post. It is easily tightened by four M3 screws which thread into corresponding captive M3 lock nuts. The only tool needed for installation is an M3 hex wrench/key. There is no need for an additional wrench or tool to install the device. The battery is mounted on the front-facing half of the device, which connects to the main body through a simple JST connector.  

The signaling switches are easily installed on the handlebar with a hinged-style clamp, using the same M3 hex wrench/key to tighten. This design accommodates for a large range of handlebar diameters. The wires can then be wrapped around the brake wires, and routed toward the frame of the bicycle, where they meet with two JST connectors which lead back to the main device.  

Inside the main device, there is a micro-controller, attached to the faceplate which can easily be removed in order to access to the USB port, allowing for maintenance, or updates to the code.  

This is a video of how the turn signals look when activated:

This is a video of random interviewees answering a few questions from our key criteria

Novel aspects:

Some novel aspects of the device include the aesthetics, functionality, and compatibility with many bicycles.  

Contrary to many other alternative designs, our design follows more of the design language of a bicycle. The long and narrow shape of the body helps it blend in with the design of a bicycle, compared to many of the flat, un-aerodynamic alternative designs sold online.  

The turning lights on the faceplate are not only shaped in an arrow, but they are also animated to more clearly indicate the direction of the intended turn, especially from a distance. Furthermore, the inside-most LEDs are yellow, aiding in the communication of the animation.  

The nature of a clamp system for mounting allows the device to be mounted on a large range of bicycle types. Similar to how soft jaws are used in the machining industry, the added clamping jaws also entertain the possibility of printing specially shaped jaws to fit certain, unusual bicycles.  

Trade-offs:

Some of the trade-offs were the method of manufacturing, the material of the final prototype, and cost. Ideally, we would like the housing and other 3D printed parts to be injection molded to increase strength, and decrease the time needed to produce one unit. Injection-molded parts also allow for a wider range of options for materials. Currently, the device is printed in PLA, which although is very rigid, is also prone to cracking leading to total structural failure. Materials like Nylon or polycarbonate would better satisfy the needs for strength, allowing the design of the device to be slimmer. In addition, the electronics of the current prototype were comprised of a microcontroller and individual LEDs which were very time-consuming to solder. Given more time and resources, we could make custom-designed PCBs with integrated microcontroller chips and surface mounted diodes, reducing the soldering time per unit from a matter of hours to a matter of minutes. Another benefit of integrating all the components onto a singular PCB is the cost-saving, both in time and money.  

The implementation of the device also has some trade-offs. Successful implementation would require most, if not every student to purchase the device for their bicycle. This entirely depends on the desirability, which is subjective according to each student. In order to sustain a product like this, a business needs to be established, with proper marketing, packaging, and other overhead costs involved in starting a business.